Organic Thermoelectrics: Materials Preparation, Performance Optimization, and Device Integration

Summary Recent rapid development of inorganic thermoelectric (TE) materials has aroused enthusiasm for exploring low-cost, flexible, lightweight, and non-toxic organic TE materials. Great progress has been achieved in developing organic materials with high TE performance (figure of merit, ZT) over the past decade. However, it is still extremely challenging to obtain organic materials with high TE performance and a ZT over 0.5 because of the strong interrelationship between the three TE parameters: electrical conductivity, Seebeck coefficient, and thermal conductivity. In this review, we discuss current trends in developing strategies to decouple the electrical conductivity, Seebeck coefficient, and thermal conductivity, which to the best of our knowledge have not been discussed in previously published reviews. Methods such as solvent treatment, electrochemical doping, and nanostructure formation are analyzed. In addition, incorrect thermal conductivity values for highly electrically conducting organic materials are still frequently reported, even in papers published in high-impact journals. A description of this puzzling phenomenon is provided in this review. Finally, a discussion of the advantages of state-of-the-art fabrication techniques of organic TE modules is presented, which highlights the unique advantages of organic TE materials in supporting wearable/portable devices.